1. Field of the Invention
The present invention pertains to tools for applying films to smooth surfaces, e.g. adhesive films to glass surfaces, in particular solar films for automotive windows.
2. Discussion of Relevant Art
Various types of films for covering or altering many types of surfaces have been used for many years. Wallpaper and other wallcovering materials such as self-adhesive films or films which adhere to surfaces through static electrical effects are one category. An increasing variety of films are being used to decorate or alter the light transmission properties of glass surfaces, flat and curved, residential/commercial through auto safety glazing. Some of these films are used to “darken” the glass by reducing light transmission; others affect work or living space environments by controlling heat gain and reducing solar radiation-caused fading, while other films may serve additional functions of enhancing safety and security, much as safety glass auto windshields prevent shattering. The application of any of these films can be difficult, and is a laborintensive, tedious process, which may explain why “paperhangers” are cited as ultimate examples of busy persons. Common problems include the formation of bubbles or folds in the films during application and ripping or otherwise damaging the films. The application of adhesive films poses the problem of applying them smoothly to the surface to be covered and trimming off any excess material before the adhesive sets. Application to auto glass surfaces, which can be curved convexly or concavely, even including compound curvatures, can be particularly difficult, requiring a significant amount of training for workers in this industry. When installing a film onto a concave surface, such as the inside surface of a car window, common problems reside in the fact that the technician is applying a flat film to a curved surface. The inherent tension on the film to conform to the curved surface of the glass promotes the formation of bubbles or fold-fingers in the films during application. Additionally, the technician must remain cognizant of the relative fragility of the medium and use care not to cause any ripping, creasing, scratching or other damage to the films. The application of adhesive films poses the problem of applying them smoothly to the surface to be covered and trimming off any excess material before the adhesive sets.
Squeegees, rollers and similar tools can be used in applying many of the films discussed above, but no ideal tool appears to be available. Problems persist in attaining the goal of smooth application of films to the surfaces requiring them, without involving the problems discussed above. A number of patents have been reviewed which are directed to squeegees, scrapers and the like.
Design Pat. No. 332,160 discloses a triangular squeegee with straight edges which is thicker in the middle and symmetric, the opposite sides being mirror images.
Design Pat. No. 364,719 discloses a roughly triangular cleaning tool with two rounded corners, a raised central portion and a generally flat bottom.
Other patents uncovered during the search which may also be of some interest, include the following:
Design Pat. No. 392,078 discloses an auto window scraper with a curved, narrow working edge and a symmetric profile.
Design Pat. No. 410,309 discloses a scraping tool having five edges, one of them “arcuate” (convexly curved), a raised central portion and a flat bottom.
Design Pat. No. 261,601 discloses a pan cleaner with both straight and curved edges, a raised central portion and a flat bottom.
U.S. Pat. No. 1,388,282 discloses a generally triangular cooking vessel wipe having two straight edges and one rounded edge with a thickened central portion and a symmetric cross section. The article is molded of non-porous rubber, and the thickened center is designed to provide “the degree of stiffness necessary”.
U.S. Pat. No. 2,262,316 discloses a culinary scraper with celluloid blades having curved or straight edges and a removable handle.
U.S. Pat. No. 3,821,828 discloses a putty application tool with a curved edge formed by intersecting chamfered surfaces. The material is unspecified.
U.S. Pat. No. 4,784,598 discloses a drywall tool with one curved edge and a handle on top. According to the final paragraphs of column 3, the tool is made of a resilient, flexible material selected for a particular hardness or stiffness. The operation of the tool with its tapered edge is shown in FIG. 7.
U.S. Pat. No. 4,919,604 discloses a finishing tool having an arcuate blade with a central spine and a handle. The blade has a tapered, deformable edge and is flat on the bottom. Its flex properties are described in column 3.
U.S. Pat. No. 5,475,199 discloses a heater for sealing thick plastic films, having a roughly triangular shape like a flatiron.
U.S. Pat. No. 2,261,063 discloses a conventional putty knife with a handle.
U.S. Pat. No. 2,046,599 discloses a scraper with both straight and curved edges, a symmetric cross section and an angled handle.
Although a variety of tools and devices are available for the application of films to various surfaces, in particular for the application of films to glass surfaces such as automotive windows, problems persist in successfully applying such films to curved auto windows without tearing or otherwise damaging the films or leaving bubbles, creases or other defects in the films once applied and adhered to the windows.